This study is open to all patients with a diagnosis of acute promyelocytic leukemia (APL) who are PCR positive for the PML-RARα transcript or rarer retinoid sensitive subtypes (i.e. NPM-RARalpha, NuMA-RARalpha) and less than 21 years of age (for AIEOP, see appendix A). APL is a rare disease with each national group recruiting small numbers of patients to their trials annually. Therefore this will be an international study expecting to recruit 60-70 patients per annum and a total of 300 patients in 5 years. The study aims to limit the use of anthracyclines and stratify treatment by risk group: standard risk - WBC <10 x 109/l : high risk - WBC ≥10 x 109/l. All-trans retinoic acid (ATRA) is included in all phases of therapy and intermediate dose Ara-C (IDARAC) is given during consolidation treatment. Following one induction course of treatment standard risk patients have 2 consolidation blocks whilst high risk patients have 3 consolidation blocks.